If you don't have git config github.user and git config github.password set in your git config, it will use unauthenticated API requests, which has a rate-limit of 60 requests. If you add your user + password info it should allow 5000 requests before you hit the limit.

You must be standing in a directory that is a git dir and that directory must have a remote that points to github.com for the tool to work.

The code is open to the world, and available for you to hack on. Please feel free to browse it and play with it, or whatever. If you want to contribute patches, please send me a diff or prod me to pull from your repository :)